Question

1.       You are planning to run a fermenter to produce antibiotics from fungi, using a fermentation broth that contains 15 wt% glucose, 6 wt% phosphate, 6 wt% nitrate, various trace nutrients, and water. At 8 a.m. the fermentor is filed with 6000mL broth and some antibiotic-producing fungi. Over the course of the fermentation, additional broth is pumped into the fermentor at 200 mL/h. The cells consume glucose at a rate of 35 g/h, phosphates at a rate of 13 g/h, and nitrate at a rate of 12 g/h. The fermentation is stopped when the concentration of one of these three nutrients goes to zero ( because the cells can no longer grow). Which nutrient-glucose, phosphate, or nitrate-will be depleted first? When is the fermentation stopped? What is the concentration (g/L) of the other two nutrients in the fermenter at the end of the run? Assume broth density is 1 g/mL.

Answer 1